What is a
“convection
cell”?
A laboratory experiment from the
Little Shop of Physics at
Colorado State University
Reach for the sky.
Overview
In this demo, students can observe a number of
small convection cells, which will help them
visualize what is occurring in the atmosphere
and oceans, Convection cells are a mechanism
to transport energy to the escape zones of the
world.
Theory
CMMAP
Necessary materials:
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One hot plate
One round metal fry pan or cake pan
Silicon oil
Aluminum powder
Rubber spatula
The aluminum powder and silicon oil are crucial
to this demo. We obtained ours from the chemistry supply stockroom at CSU.
Convection cells have an important role in
thunderstorms and other weather phenomenon. Convection cells occur due to that fact
that the earth is heated differentially. At the
poles, sunlight shines at an angle and is spread out over a much larger area. This creates a high pressure
area of colder, denser air. As the cold air sinks, it becomes even colder. It moves away from the poles to
low pressure areas with warmer, less dense air. This warm air is pushed up by the buoyant force of the
colder denser air. As the warm air rises, it cools, and the convection cell recycles itself, over and over
again.
Doing the Experiment
IMPORTANT SAFETY NOTE: The hot plate,
pan, and oil can become very hot. Please warn
students to be careful around these two items
when observing the demo.
• Turn on the hot plate to low.
• Mix the aluminum powder into the silicon oil and
pour it in the pan.
• Place the pan on the warm hot plate.
• Have students observe as the magic of the convection cells happens!
• Discuss the dark spot in the middle of each cell
and what is occurring.
Summing Up
Convection cells happen on the surface of the sun too.
The atmosphere is all about the movement of energy.
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This demonstration is a way to have students observe a method that the atmosphere uses to transport energy from one area to another.
For More Information
CMMAP, the Center for Multi-Scale Modeling of Atmospheric Processes: http://cmmap.colostate.edu
Little Shop of Physics: http://littleshop.physics.colostate.edu
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